GSK, which is Britain’s biggest drugmaker and the sixth-largest pharmaceuticals group in the world in terms of sales, said it is “committed to operating its business to the highest ethical standards and will continue to cooperate fully with the SFO”.

In an apparent plea for more information from GSK insiders, the SFO said that whistleblowers were a valuable source of information and it welcomed approaches “from anyone with inside information on all our cases including this one”.

The SFO action comes less than two weeks after Chinese police announced on May 14 that they had charged the former British boss of GSK’s China business and other colleagues with corruption, after an investigation there allegedly found evidence of an elaborate scheme to bribe doctors and hospitals.

The 2010 UK Bribery Act prohibits payments to government officials, including state-employed doctors, to obtain business overseas.

However, GSK could claim mitigation against prosecution if it can demonstrate that it had robust policies and procedures in place that were circumvented by rogue employees.